Hm. I got the impression that "derived work" was actually defined
differently for the LGPL as compared to the GPL. Is that true, or
does the LGPL have to explicitly exempt certain derived works?
The definition of derivative work comes from copyright law,
but in certain issues there is no clear definition yet.
The LGPL explicitly exempts certain kinds of works,
saying that even if they do count as derivative under the law,
we will not apply to them the same requirements that we apply
to other derivative works. There is no doubt that the copyright
holder can do that.